The invention relates to a surface treatment plant for motor vehicle bodies, having    a) a first treatment area which comprises a first conveyor system by means of which a motor vehicle body can be conveyed through the first treatment area;    b) a second treatment area which comprises a second conveyor system by means of which the motor vehicle body can be conveyed through the second treatment area.
The invention relates in addition to a method for conveying motor vehicle bodies through a surface treatment plant, in which a motor vehicle body is conveyed by means of a first conveyor system through a first treatment area and by means of a second conveyor system through a second treatment area.
After construction of the shell, motor vehicle bodies are subjected to a surface treatment, which comprises in total a relatively large number of individual treatment steps. Consequently, a surface treatment plant for motor vehicle bodies comprises many different treatment areas, through which the motor vehicle bodies that are to be treated must pass in a fixed order.
In surface treatment plants known on the market, the motor vehicle bodies are conveyed into different treatment areas by means of different conveyor systems that are adapted to the particular treatment in question.
A treatment area can also comprise a plurality of treatment regions in which different types of treatment can be carried out, but the conveyor system does not change. As long as the motor vehicle bodies are conveyed through successive treatment regions by means of one and the same conveyor system, those treatment regions belong to one treatment area.
A surface treatment plant for motor vehicle bodies comprises, for example, the following treatment areas TA, which may be divided into treatment regions denoted TR and between which a transfer region is arranged in each case:
TA-1TR-1Pretreatment (one or more dip tanks)TR-2Cataphoretic dip coating (CDC)Transfer regionTA-2CDC drierTransfer regionTA-3TR-1CDC auditTR-2CDC polishingTR-3Seam sealingTransfer regionTA-4UndercoatingTransfer regionTA-5FillerTransfer regionTA-6Filler drierTransfer regionTA-7TR-1Filler auditTR-2Filler polishingTransfer regionTA-8Top coatTransfer regionTA-9Top coat drierTransfer regionTA-1TR-1Top coat auditTR-2Spot repairTR-3Cavity sealing
In a transfer region, the motor vehicle body is transferred from the conveyor system of a first treatment area to the conveyor system, which is different therefrom, of a subsequent, second treatment area.
In surface treatment plants known on the market, the motor vehicle bodies are secured to so-called skids and conveyed through the individual treatment areas. The skid with the motor vehicle body is normally transferred from a first conveyor system to a second conveyor system, which conveyor systems both cooperate with the skid but are structurally different, because different treatment areas mostly also require different conveyor systems. Examples which may be mentioned are an electrified monorail system for dipping treatment and a chain conveyor for a drying operation.
In the individual treatment areas, such a skid in most cases undergoes the same treatment as the motor vehicle body secured thereto. Accordingly, in the first treatment area designated TA-1 above, for example, a skid is guided together with the motor vehicle body through the dip tanks that are present. Some of the treatment liquid is accordingly also used for the skids.
The motor vehicle body also traverses the subsequent CDC drier in treatment area TA-2 on a skid. Accordingly, with each motor vehicle body, the associated skid is also heated up each time and is subsequently allowed to cool down again with the motor vehicle body. As a result, a considerable amount of energy is used in each drying operation for heating the skid.
In treatment areas in which the skid does not undergo any direct material treatment, it must nevertheless be carried together with the motor vehicle body. The total mass of the motor vehicle body and the skid that is to be conveyed is accordingly considerably higher than the mass of a motor vehicle body alone. For example, a motor vehicle body weighing approximately 400 kg is conveyed on a skid that weighs approximately 150 kg. Because greater masses have to be moved, more energy must also be utilised for transporting the motor vehicle body and the skid than for transporting a motor vehicle body on its own.
Overall, in the case of the conventional techniques of conveying motor vehicle bodies with a skid, the overall energy balance in respect of the motor vehicle bodies that are to be treated is impaired and the overall operating costs of the plant are accordingly increased.
Accordingly, it is an object of the invention to provide a plant and a method of the type mentioned at the beginning which take that idea into account.